The United States and China are the world’s two largest economies. They are also the two largest producers and consumers of coal, and the largest emitters of carbon dioxide. In recent years, however, their paths on coal have started to diverge.

Over the last few years, coal consumption has dropped dramatically in the United States, mainly due to low natural gas prices. In response to weak domestic demand, the U.S. coal industry has been rushing to find its way out to the international market. Last year, U.S. coal exports hit a historical high of 114 million metric tons.

However, it is worth noting that the shift away from coal in the U.S. may not be permanent. As my colleague, Kristin Meek, pointed out in an earlier blog post, coal use in the U.S. power sector was on the rise again towards the end of 2012, likely driven by the new uptick in natural gas prices.

On the other side of the globe, China’s appetite for coal continues to grow. In response, Chinese power companies are looking to tap the international coal market for sources that are more reliable and cost competitive. Among those markets is the United States. In 2012, China imported 290 million metric tons of coal. China was the third largest destination for U.S. coal exports, behind the Netherlands and the U.K.

This post originally appeared on the National Journal's Energy Experts blog. It is a response to the question: "What's holding back energy and climate policy?"

We are in a race for sure, but it is not a race among various national issues. It’s a race to slow the pace of our rapidly changing climate. The planet is warming faster than previously thought, and we cannot afford to wait for national politics to align to make progress in slowing the dangerous rate of warming.

Recent events, like the tragedy at Sandy Hook elementary school, propelled gun control front and center. Last year’s elections shifted the national conversation on immigration. Climate change, too, should demand the attention of our national leaders.

The evidence of climate change is clear and growing. In 2012, there were 356 all-time temperature highs tied or broken in the United States. As of March, the world had experienced 337th consecutive months (28 years) with a global temperature above the 20th century average. Global sea levels are rising and artic sea ice continues to shrink faster than many scientists had predicted.

There are indications that Americans are deepening their understanding about climate change, especially when it comes to its impacts. People are beginning to connect the dots around extreme weather events, rising seas, droughts and wildfires, which have been coming in increasing frequency and intensity in recent years. The National Oceanic and Atmospheric Administration calculated that weather-related damages in the United States were $60 billion in 2011 alone.

Since the very first Earth Day more than four decades ago, the environmental movement has tackled a wide range of problems, including air pollution, contaminated water, deforestation, biodiversity loss, and more. But this Earth Day, I propose that there are two fundamental issues the movement must address over the coming decade if it is ever to defuse the tension between development and the environment. In fact, these two issues underlie many, if not most, of the world’s environmental challenges.

Unsustainable Food Production

Food production has significant―but often underestimated―impacts on the environment. Take climate, for instance: About one-quarter of the world’s annual greenhouse gas emissions are agriculture-related. In particular, nearly 13 percent of global emissions comes from livestock, fertilizer use, and farm-related energy consumption, while another 11 percent results from the clearing of forests and other ecosystems, primarily for agriculture.

Ministers are gathering in New Delhi today to address an urgent challenge: how to unlock the full potential of clean energy to drive economic growth, expand energy access, and protect the climate. The 4th Clean Energy Ministerial — which brings together energy ministers and other delegates from more than 20 leading economies — is a critical opportunity to inject new life into the global clean energy transition.

While we've seen progress on renewable energy, the sector still faces barriers to increase financial support and create strong national policies that will enable it to flourish. First, some good news: The renewable energy market has blossomed in recent years. In just the last decade, global clean energy investment has increased five-fold, from $50 billion a year to more than $250 billion. And more than 100 countries have renewable energy targets in place.

India has set itself on a remarkable journey by ushering in renewable energy growth. The National Action Plan on Climate Change, launched in 2008, aims to have 15 percent of India's electricity consumption from renewable energy by 2020. Currently, the country produces slightly more than 12 percent of its energy from renewables, putting it on track for that goal. India has been using various policy levers to advance renewable energy, including tax and generation-based incentives, capital subsidies, and feed-in tariffs. The Renewable Portfolio Obligations is also providing support for renewable energy developers. Even so, the country is not yet achieving its full potential — which is critical for the 400 million people who lack access to basic electricity.

The rapid expansion of natural gas development in the United States has been a double-edged sword. While natural gas supporters are quick to point out its economic benefits and green attributes—natural gas produces roughly half the carbon dioxide emissions of coal during combustion—this isn’t the whole story. Natural gas comes with environmental consequences, including risks to air and water quality.

One risk is “fugitive methane emissions,” potent greenhouse gases that escape into the atmosphere throughout the natural gas development process. This methane—which is 25 times more potent than carbon dioxide over a 100-year timeframe—contributes to global warming and undercuts the climate advantage that cleaner-burning natural gas has over coal and diesel. (Learn more about fugitive methane emissions in our recent blog post.)

Despite the controversy surrounding natural gas development, energy forecasts suggest that natural gas is here to stay. Fortunately, several pathways are available to limit the climate impacts associated with its development. WRI just released a working paper, Clearing the Air: Reducing Upstream Greenhouse Gas Emissions from U.S. Natural Gas Systems, which outlines a number of state and federal policies and industry best practices to cost-effectively reduce fugitive methane emissions. We find that with the right amount of reductions, natural gas does offer advantages from a greenhouse gas (GHG) emissions perspective over coal and diesel.

Natural gas is booming in the United States. Production has increased by 20 percent in the last five years, fueled largely by technological advances in shale gas extraction. Other countries--including China--are now studying our experience with this abundant new resource.

But the growing role of natural gas in the U.S. energy mix hasn’t come without controversy. Natural gas development poses a variety of environmental risks. In addition to habitat disruption and impacts on local water and air quality, one of the most significant concerns is the climate impact resulting from the “fugitive methane emissions” that escape into the atmosphere from various points along the natural gas supply chain.

So what are fugitive methane emissions, and how big of a problem are they? How do emissions from natural gas compare to those from coal? And are there ways to mitigate them? The answers to these questions will help us better understand how natural gas development will affect climate change.

Developing countries will need about $531 billion of additional investments in clean energy technologies every year in order to limit global temperature rise to 2° C above pre-industrial levels, thus preventing climate change’s worst impacts. To attract investments on the scale required, developing country governments, with support from developed countries, must undertake “readiness” activities that will encourage public and private sector investors to put their money into climate-friendly projects.

The development of Thailand’s energy efficiency sector is an interesting case study. It demonstrates how strong government leadership combined with strategic support from international climate finance can drive the transition toward an energy-efficient economy.

In the early 1990s, Thailand’s economy was growing rapidly at 10 percent per year; the power sector was growing even faster. The government recognized that conserving energy would provide a low-cost way to meet its citizens’ rising demand for energy.

New data from the U.S. Energy Information Administration (EIA) reveals a troubling trend: Coal-fired power generation—and its associated greenhouse gas emissions—were on the rise as 2012 came to an end.

According to the data, which was released yesterday, natural gas prices have risen significantly since April of 2012, prompting a rise in coal-fired electric generation (see figure below). This increase marks a dramatic change from the trends we’ve seen in the United States over the past several years. U.S. energy-related carbon dioxide (CO2) emissions from the power sector had been falling, mostly due to more electricity being generated by renewables, slowed economic growth, and a greater use of low-cost natural gas, which produces roughly half the CO2 emissions of coal during combustion.

The new uptick in gas prices and coal use suggests that we cannot simply rely on current market forces to meet America’s emissions-reduction goals. In fact, EIA projects that CO2 emissions from the power sector will slowly rise over the long term. To keep emissions on a downward trajectory, the Administration must use its authority to prompt greater, immediate reductions by putting in place emissions standards for both new and existing power plants.

America is blessed with abundant energy sources, from an array of traditional fuels and natural gas to solar, wind, and other renewable resources. But as the pressure on these resources grows, the United States must have a plan to ensure a stronger and more sustainable future. In today’s world, any smart and effective energy strategy must take into account the risks of climate change.

Climate change impacts are already here. They do not have a political affiliation, nor are they constrained by state boundaries. Moreover, climate impacts are taking a serious toll on America’s infrastructure and economy.

Let’s look at some examples:

America’s coastal areas are particularly vulnerable, as rising sea levels and heavier precipitation are increasing the impacts of hurricanes and other storms. More than 58 percent of U.S. gross domestic product, some $8.3 trillion, is generated in coastal areas (including the Great Lakes). This accounts for some 66 million jobs. Florida, in particular, faces significant threats due to rising seas.